This invention relates to optical systems in general, and more particularly to methods and apparatus for optically connecting components in optical systems.
Vertical cavity surface emitting lasers (VCSELs) that are adapted for use at longer wavelengths (e.g., 1310 nm and longer) are generally relatively difficult to make and tend to have relatively low output power. Amplification of the largest output signal may be necessary in order to boost the power to the level necessary for telecommunications or other applications. One method for achieving this amplification is to co-package a semiconductor optical amplifier (SOA) with the VCSEL in a module, with the coupling between the VCSEL and the SOA being achieved by free space optics. However, effecting proper alignment of the VCSEL, SOA and intervening optics can be difficult.
As a result, one object of the present invention is to provide a method and apparatus for quickly and easily effecting proper alignment of the VCSEL, SOA and intervening optics.
These and other objects are addressed by the provision and use of the present invention which, in one form of the invention, comprises a method for integrating a VCSEL with a SOA, comprising: positioning a collimating lens adjacent to the output of the VCSEL, positioning a focusing lens adjacent to the input of the SOA, and positioning a movable lens between the collimating lens and the focusing lens, where the movable lens has a focal length significantly longer than the focal length of the focusing lens; and moving the movable lens relative to the focusing lens so as to adjust the focusing spot on the input of the SOA.
In another aspect of the invention, there is provided apparatus for integrating a VCSEL with a SOA, comprising: a collimating lens positioned adjacent to the output of the VCSEL; a focusing lens positioned adjacent to the input of the SOA; and a movable lens positioned between the collimating lens and the focusing lens, where the movable lens has a focal length significantly longer than the focal length of the focusing lens.
And in another aspect of the invention, there is provided a method for integrating a VCSEL with a SOA, comprising: providing a VCSEL and providing a SOA; and butt-coupling the output coupler of the VCSEL to the input facet of the SOA, wherein the output facet of the SOA is angled with respect to the input facet of the SOA and the input facet of the SOA is anti-reflection coated to prevent excessive feedback to the VCSEL.
And in another aspect of the invention, there is provided an assembly comprising: a VCSEL; a SOA; the output coupler of the VCSEL being butt-coupled to the input facet of the SOA, wherein the output facet of the SOA is angled with respect to the input facet of the SOA, and the input facet of the SOA is anti-reflection coated so as to prevent excessive feedback to the VCSEL.